Shearable counter knife



2, 1955 G. MGLLER SHEARABLE COUNTER KNIFE Filed Sept. 4, 1952 Fig. 4

INVENTOR:

United States Patent 2,714,410 SHEARABLE COUNTER KNIFE Georg Miiller, Geesthacht, Germany Application September 4, 1952, SerialNo. 307,820 3 Claims. (Cl. 146-119) The present invention relates to improvements in tobacco cutting machines and is particularly concerned with the arrangement of the counter knife on a tobacco cutting machine, especially a cutting machine with a rotary head. According to the invention the counter or lower knife is sheared from the lower part of the mouthpiece, to which it is connected for example by means of screws, especially when a hard foreign body is present in the tobacco stream and a cutting knife runs against it.

It may happen that for example a foreign body is fed forward into the tobacco cutting machine and when it comes into range of the cutter knife, the latter is so seriously damaged that it is unusable for a long time or the knife is distorted so that other parts of the machine are damaged on continued running thereof. Since the rotary knife head has a considerable speed, in general all the knife blades are damaged, for it requires a certain time to bring knife head to a standstill. It has therefore proved to be advantageous if the counter knife (bottom knife) is so fitted to the frame or to the lower part of the mouthpiece that it can yield if the pressure is too great. Thereby the knife is saved, further damage does not occur and after a comparatively short time the machine is again ready for use.

If the counter knife is sheared off by too great a pressure a switch device can also be brought into operation by which the machine is stopped or first slowed down.

If the knife is sheared off, it falls downwardly and in order that the knife shall not fall into the tobacco it may also be made captive, being connected to the machine frame by means of a chain. In prior art machines, after shearing the screw heads also fall into the tobacco. To avoid this, the screw heads according to the invention are preferably drilled and connected by means of a wire. knife by means of screws so that the screw heads, even if out off, cannot fall into the tobacco but are retained together with the counter knife by the chain.

The accompanying drawings show one constructional example of the invention by way of example and in which Fig. 1 shows the mouthpiece section of a rotary tobacco cutter in section,

Fig. 2 is a section through the counter knife with a shear screw,

Fig. 3 shows the lower section of the mouthpiece after the under knife has been removed, and

Fig. 4 is a view of the mouthpiece and the tobacco stream as seen from the knife drum.

In the rotary drum tobacco cutter 1 indicates the tobacco leaves which are fed along the endless feed chains 2 and 3 towards the rotary knife head 4. The feed chains 2 and 3 are actuated by the conveyor rolls 5 and 6 which in turn are supported on shafts 7 and 8. In the side view a single knife 9 is indicated only on the rotary head. 10 represents the upper mouthpiece jaw which can be reciprocated up and down The wire is in turn fixed to the lower through a drive mechanism not show. The lower part 11 of the mouthpiece, atthe forward edge of which the counter knife 12 is located, carries the said knife by means of screws 13 engaging. the plate 11. The screws 13 have a suitable cross section so that for an excessive pressure the screw heads are sheared off. Normal screws may also be used for the screws 13, which for example are drilled out in the longitudinal direction in order to weaken the cross section. Instead of screws also or additionally the so-called shear pins can be utilised. The plate 14 in turn is screwed to the lower part 11 of the mouthpiece. A hole is drilled in. the screw heads 13 through which a wire 15 is passed which connects the screw heads one with the other. This wire is for example connected by a screw 16 with the counter knife 12. A chain 17 is fitted laterally to the counter knife which chain is fixed to the frame. If the counter knife is sheared off it, together with the screws 13, cannot fall into the cut tobacco beneath it.

Behind the counter knife 12 a switch 18 is provided embodying a bolt 19 with a flange 20 against which a coal spring 21 bears. The coil spring presses the bolt continuously towards the counter knife 12. Facing the flange 20 are two contacts 22 which are connected by wires 23 for example to an electric supply source. When the counter knife 12 is sheared 01f (see Fig. 3) the bolt 14 moves forward and by the flange 20 provides a connection between the two contacts 22 so that the machine is stopped or retarded before stopping.

Instead of using the wire 15 a cap could be provided over each screw head, which is fixed to the counter knife, so that the sheared off heads cannot fall into the tobacco.

What I claim is:

1. A tobacco cutting machine comprising a frame, a cutter drum rotatably mounted in said frame, at least one knife mounted longitudinally of the periphery of said drum, a substantially rectangular mouthpiece having upper and lower jaws mounted adjacent the periphery of said drum, a pair of opposed conveyors mounted in said frame to feed tobacco leaves into said mouthpiece, a counter knife supported on the lower jaw of said mouthpiece against which the shearing of tobacco is effected, headed shearable fastening means securing the counter knife to said lower portion of said mouthpiece, retaining means connecting the heads of said fastening means to said counter knife, a second retaining means loosely connecting said counter knife to said frame whereby the heads of said fastening means and said counter knife are prevented from falling into the cut tobacco in the event of said fastening means being sheared when the knife blade strikes a solid object in the tobacco, and retarding means on said lower jaw to stop rotation of said cutter drum when said counter knife is released.

2. A tobacco cutting machine comprising a frame, a cutter drum rotatably mounted in said frame, at least one knife mounted longitudinally of the periphery of said drum, a substantially rectangular mouthpiece having upper and lower jaws mounted adjacent the periphery of said drum, a pair of opposed conveyors mounted in said frame to feed tobacco leaves into said mouthpiece, a counter knife supported on the lower jaw of said mouthpiece, against which the shearing of tobacco is effected, shearable headed screws securing the counter knife to said lower portion of said mouthpiece, a retainer wire extending through holes in the heads of said screws and fastened to said counter knife, a retainer chain loosely connecting said counter knife to said frame whereby the heads of said screws and said counter knife are prevented from falling into the cut tobacco in the event of said screws being sheared when the knife blade strikes a solid object in the tobacco, and retarding Patented Aug. 2, 1955.

3 4 7 means on said lower jaw to stop rotation of said cutter cut off the electric supply to said motor and stop rotation drum when said cutter blade is released. of said cutter drum.

3. A tobacco cuttmg machine as claimed in claim 2, References Cited in the file of this Patent in which the cutter drumis rotated by an electric motor connected to an electric power source, said retarding 5 UNITED STATES PATENTS means comprising a switch consisting of a pin, slida ly 558,001 Ross Apr. 7, 1896 mounted on the under side of said lower jaw, a flange 1,079,657 McLean Nov. 25, 1913 located on said pin, a compression spring norma y co 1,735,823 Huffman Nov. 12, 1929 tacting said flange to urge one end of said pin against said 1,967,240 Guest July 24, 1934 counter knife, a pair of spaced apartelectric Wires loca ed 10 1,968,417 Morine July 31, 1934 between said flange and said counter knife and connected 2,022,135 Newhouse Nov. 26, 1935 tosaid motor, whereby when said cutter blade is re eased 2,525,795 Grisdale Oct. 17, 1950 the pin flange is brought into contact with said wires to 2,610,800 Tunley Sept. 16, 1952 

